Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Just wondering if they will fit on 550 GT with sport package? Car comes with 20" factory rims. Because I have not purchased car yet so I'd like to find out if these wheels will fit or what spec of spacers I will need.

To fit any car, the bolt pattern and size, offset, width, and diameter must all be within certain specifications. Then, the wheel must be capable of mounting the TPMS (at least in some places, you won't pass if that is not present). You may already know that, but it's lots more than just the offset that matters if it will fit. First, the bolt pattern is: 5-120, and the rest of the stuff depends very much on the specific wheel as to whether it will fit. It must be able to be bolted on, fit over the calipers, and not put excessive stress on the bearings, and to pass inspection most places, the tire edge at least on part of the wheel must be within the fenderwell when going straight ahead to keep from flinging debris out behind and becoming a hazard for those following. The tire/wheel package chosen must also be within a small variation of the factory package for the gearing, speedometer, and odometer readings to be correct.

If you're lucky, someone here will know, but you might want to check with the wheel manufacturer to see if they will fit.

and somewhere in the specs there is a minimum weight rating per wheel but unfortunately I don't know where to find this.

R

edit: at least I found something:
the weight rating per wheel is expressed in the Load Index of the tyres
so for the fronts: 99 means 750 kg, for the rears 102 means 850 kg and Y is the max Speed index of the tyre (Y = up to 300 Km/h)

Most wheels would have no problems with the max load...but, not all will fit, which I understand is the orginal question. IWO, two different wheels in the same size from two different manufacturers to fit a vehicle properly need everything to line up - the bolt pattern, the offsets, and the actual inner shaping (often determined by the machining) of the wheel so it can clear the calipers and any other suspension and frame components when turning or even straight ahead. Having the centerline of the wheel too far in or out from the design puts extra loads on the bearings, and if too far out, slings pebbles and other debris onto the car and those behind which can be quite expensive and dangerous.

I do not know what those numbers are, BMW probably won't tell you, and your best bet is to talk to the aftermarket supplier and see if they've confirmed it will fit.